DFQL: A Graphical Dataflow Query Language.

摘要

In nearly all large organizations, the Navy and Department of Defense being no exceptions, the use of database management systems (DBMS's) has become widespread. The prevailing data model for modern DBMS's is the relational model developed by Codd in the early 1970's. The relational model's superiority is due to its well thought out design and founding in mathematical logic. The de facto standard query language for relational DBMS's is IBM's Structured Query Language (SQL). Although SQL is the most widely used query language today, it has many problems, especially in the ease-of-use area. The purpose of this thesis is to design, implement, and test a new query language, DFQL, which will mitigate SQL's ease-of-use problems. DFQL provides a graphical query interface based on the dataflow paradigm in order to allow a user to easily and incrementally construct queries for a relational database. DFQL is relationally complete, maintains relational operational closure, and is designed to be easily extensible by the end user. DFQL has been implemented on an Apple Macintosh using an ORACLE relational DBMS. A simple human factors experiment was performed in which DFQL's ease of query writing compared favorably to that of SQL.